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Somatosensory functions – pain researchSomatosensory functions – pain research (Torebjörk, Schmidt): Studies of sensory functions in man had earlier been restricted since it was not possible to record signals from cutaneous sensory endings in humans. Torebjörk showed in his thesis that is was possible to study even unmyelinated C fibres. The technique was improved when Torebjörk and Ochoa introduced the so called intraneural microstimulation by which it was possible to study the correlation between impulse characteristics and subjective sensation. Microneurography from human skin nerves combined with the technique of intraneural microstimulation has made it possible to analyse the specific types of sensations aroused by neural impulse messages signalled by various types of A- and C-fibre sensory units. Studies of this type have been made both in healthy subjects and in patients with different types of paraestesias, hyperalgesias and neurogenic pain. Two types of C-nociceptors have been identified: polymodal units and mechanosensitive units activated by algogenic substances. A special type of C-units are histamine responsive and give rise not to pain but to itch sensations. The technique allows differentiation between chronic pain syndromes due to peripheral nociceptor hyperexitability or due to increased responsivness of central sensory neurones. |
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Uppsala University | Updated: 2011-08-09
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